[Les] from [Les’ Lab] has designed a driver for laser diodes up to 10 watts, and decided to show us how it operates, tells us what we should keep in mind when designing such a driver, and talks about laser safety in general. This design is an adjustable current regulator based on the LM350A, able to provide up to 10 watts of power at about 2 volts – which is what his diode needs. Such obscure requirements aren’t easily fulfilled by commonly available PSUs, which is why a custom design was called for.
He tells us how he approached improving stability of the current regulation circuit, the PCB design requirements, and planning user interface for such a driver. However, that’s just part of the battle – regulating the current properly is important, but reducing the potential for accidental injuries even more so. Thus, he talks extensively about designing the driver circuit with safety in mind – using various kinds of interlocks, like a latching relay circuit to prevent it from powering up as soon as power is applied.
Of course, safety concerns go beyond the driver’s features, and so does [Les], feeling that we should know what goes into operating a laser of such power. He explains the importance of choosing proper safety glasses for the wavelengths involved – what the various relevant numbers mean, and how to use these numbers to choose glasses actually able to protect you from going blind on accident. Mounting everything in a solid way is called for, too – you wouldn’t want the laser to accidentally move away from the path you want it to shine in, since even reflections can be quite dangerous.
In the end, [Les] shows the driver in action coupled with a laser diode, and produces enough smoke that we are legally obligated to consider this a ‘smoke test’ – a successful one! He has big plans for that diode, and we can’t wait to see them come into fruition.
[Les]’s YouTube channel has videos about all kinds of electronics-related DIY builds, and is definitely worth going through if laser-adjacent topics are of interest to you. We’ve covered a few of his builds in the past, including a Raspberry Pi-based spectrometer and a high-voltage switch out of a simple spark gap.
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